Wednesday, 23 March 2011

Presence of Mould Species Correlate with Presence of Asthma

Last week we featured a paper that appeared to demonstrate that the presence of some moulds at a very early age correlated with the lowering of the susceptibility of children to asthma in later life. The authors postulated a 'protective effect' caused by the triggering and presumably modulation of infection response pathways involved in atopy and asthma.

In that paper the 'mouldiness' of the houses examined was determined by the collection of dust samples from those houses.

A new paper takes a look at this method of sampling, its accuracy and reliability and compares it to the results of a newly developed test based on Polymerase Chain Reaction technology (PCR). This new test looks at the DNA 'signatures' left by more than 100 specific fungi and can accurately detect and reliably identify each species and how much of each species is present (mould specific quantitative PCR (MSQPCR)).

Older, traditional technology is fraught with potential difficulties and sources of inaccuracy and in some ways the new test is inherently more accurate, faster and gives us more information. Both still rely on dust samples which may or may not be representative of current mould levels in any house at a particular time but they can usually be a reasonable guide to the overall state of mouldiness of a house.

MSQPCR was used to compare mould levels in damp houses with those in dry houses and was able to develop an index of which mould species tend to be associated with damp houses - the Environmental Relative Mouldiness Index (ERMI).

Using this index the researchers found that houses suffering from moulds that are present in damp houses tend to house children with asthma - that is to say particular moulds correlate with asthma in children.

You might now be saying "This is the opposite conclusion to that made by the paper we covered last week isn't it??". In fact the paper published last week was making its conclusions based on information that was not as detailed as this new paper. In that paper they could not differentiate individual species and it is the precise finding of this new paper that only specific species are correlating with damp & asthma. The findings of the first paper where that a particular group of moulds (possibly containing dozens of species) correlates with lack of asthma, but we don't know which species are involved, only that a broader range of species are involved compared with homes that are associated with atopy & asthma.

This second paper effectively follows on from the first rather than disagrees. Hopefully now that we have been able to start to identify 'bad' moulds (as mentioned last week) we will be able to make more progress in preventing childhood asthma.


Ian Cull said...

Please update your link to the new paper. It appears to be broken.

Website Team Graham said...

Sorry about that error - the blogger system isn't letting me edit for some reason so until I can correct it the valid link is

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